The present invention relates to fuel injection pumps of the distribution type wherein a plunger having a spill port is driven by the output shaft of a Diesel engine to determine the end timing of injected fuel, and more specifically to a fuel injection pump having a compact spill-port timing control unit.
The spill-port timing control unit of known distribution type fuel injection pumps for Diesel engines comprises a spill ring movably mounted on the rotary plunger of the pump and a centrifugal governor that axially moves the ring to bring its spill port into alignment with a spill port of the plunger to allow compressed fuel to escape through the aligned ports to the outside at the end of fuel injection. Another type of spill-port timing unit which has been developed to replace the governor type unit comprises a rotary or linear solenoid having a moving part which is linked to the spill ring by a mechanical means such as levers. This resulted in a relatively complicated mechanism and takes up a substantial amount of space in the fuel pump housing, and as a result the injection pump became bulky. It has therefore been desired to develop a spill-port timing control unit that is easy to manufacture and compact in design without sacrificing the required degree of sensitivity to a control signal applied to the solenoid.